Loud "air Horn" noise from Shaft area

[Patha1]

Problem solved - Update

Finally resolved the loud air horn type noise at high rpm - It was a loose clamp on the turbo intake hose. The noise shot backwards and sounded like it was coming from the stern area, but actually was at the engine turbo. Our technician put a pressure test on the system and found it.
Major clue was that we were only able to get 10 - 11 kts at WOT, indicating that the turbo was not functioning. Also this is exactly when the noise occurred.
Thanks to everyone who offered help.

 

[Patha1]

Loud Air horn noise Problem solved - Update

Finally resolved the loud air horn type noise at high rpm - It was a loose clamp on the turbo intake hose. The noise shot backwards and sounded like it was coming from the stern area, but actually was at the engine turbo. Our technician put a pressure test on the system and found it.
Major clue was that we were only able to get 10 - 11 kts at WOT, indicating that the turbo was not functioning. Also this is exactly when the noise occurred.
Thanks to everyone who offered help.

 

[rgano]

It is always good when somebody like you follows up -best way for us all to support one another!